Skype is down. Again.

Oh dear. Skype is down, at least for an awful lot of users around the world.

Many users can't sign in at all, and those that can are having trouble making and receiving calls or text-based chat.

The company's acknowledged the problem - although not, perhaps the scale of it - on its Heartbeat blog.

"A small number of you may have problems signing in to Skype. We’re investigating the cause, and hope to have more details to share soon," it says.

Some Twitter users are suggesting that the outage might have sometihng to do with Microsoft's acquisition of the company - fast work, if so, as the deal hasn't actually closed yet.

Last December, Skype suffered a massive outage, caused by the failure of thousands of 'supernodes', which aggregate and route traffic. This was triggered by a software update. And a week ago, there was a less widespread outage, which still lasted for most of a day.